The present invention relates to a memory card designed for reception in a memory card receptacle and into or from which information is written or read, the memory card having erasure prevention.
A well-known memory card incorporating memory chips in which information signals are stored is provided with terminals which are to be electrically connected with an external system. The memory card is supplied with a voltage through the terminals and also delivers and receives information signals to and from the internal memory chips through the terminals.
Since the terminals for connection of the memory card to an external system are also electrically connected to the internal memory chips, they should be protected from being touched when the memory card is used. More particularly, if the terminals are directly touched, a static electricity will take place in them, which although rare, will be transmitted from the terminals to the memory chips, thereby causing damage. To avoid this, the terminals should be protected against easy access from outside.
Also, a desirable feature of the memory card of this type is its transportability. To design more compact memory cards, thus taking advantage of their portability, their terminals have been designed to be thinner and closer together.
Such thin, closely disposed terminals for connection to an external system will possibly be deformed and broken even if just lightly touched.
To prevent the terminals from being deformed or broken, it has been proposed to bury such terminals inside the memory card body and small holes communicating with the terminals are formed in the memory card body so that the terminals are exposed only through the holes. In another proposal, a concavity is formed in a forward, or leading, end portion of the memory card body and terminals are disposed in the bottom of the concavity where they are protected.
However, the memory card in which the terminals are exposed through small holes is difficult to disconnect from a receptacle therefor if the holes are clogged with dust or the like. When the memory card is inserted into the receptacle with clogged holes, no positive connection with the receptacle can be attained and also the terminals of the receptacle may possibly be deformed.
Further, the above memory card is apt to have a complicated structure and is expensive to manufacture. Therefore, this type of memory card is not suitable for mass production.
Also, in the memory card having a concavity in the body in which the terminals are disposed, the terminals cannot be satisfactorily protected if the concavity is improperly shaped. For example, dust or the like is likely to heap or stay in the corners of the concavity and block the terminals of the memory card from secure connection with the terminals of the receptacle.
As a data storage device, the memory card should have an erroneous erase prevention switch for preventing erroneous erasure of data stored therein. However, if the erase prevention switch is provided on a main plane of the memory card body, a user cannot operate the switch when the memory card is mounted in the receptacle of an electronic apparatus. For example, if the memory card is inserted into an electronic apparatus and the user finds that the memory card is disabled for writing (that is, erasure is prevented), the user cannot write new data over data already stored. The user must eject the memory card from the electronic apparatus, set the erase prevention switch to a write state, and then re-insert the memory card into the electronic apparatus. This is inconvenient, troublesome and often frustrating.
The present invention has as an object to overcome the above-mentioned drawbacks by providing a memory card having a simple structure, adapted to positively protect the terminals thereof and attain a positive connection with a memory card receptacle.
Another object is to provide a memory card capable of preventing erroneous erasure or over-writing of stored data while enabling the erase prevention switch to be set to a desired mode, or state.
The above objects can be accomplished by providing a memory card comprising a rectangular shaped body, a concavity open at the top and formed proximate the leading edge of the card body, and terminals disposed in the concavity. The memory card has also a projection, or rib, formed in at least a part of the space between adjacent terminals in the concavity to protect the terminals from being touched from the outside. The projections define sockets in which are disposed respective terminals.
In one embodiment, the memory card according to the present invention includes a storage device for storing data supplied from the terminals by external apparatus, a switch settable to inhibit the writing of data into the storage device, and a control device for controlling writing of data into the storage device.
In the memory card, the switch can be operated even when the memory card is mounted on or received by the external apparatus; and the control device detects the state of the switch when data from the control apparatus is to be written into the memory card, thereby sending a write enable signal to the external apparatus when the switch is set to a write mode, and sending a write disable signal to the external apparatus when the switch is set to a write disable mode. For example, the external apparatus may include a data store; and when a write enable signal is received from the memory card, data stored in the data store is read out and written to the memory card, whereas when a write disable signal is received from the memory card, read out of the data from the data store is inhibited.